add avatar image soppurt

[NatanAnter]

No description provided.

[eliiran1231]

nice job
one small issue though. the current approach determines wheatear the avatar is an image solely by the value which can be vague and cost performance,
it would be better to create an avatar type in chats.ts that would look something like

export type Avatar = {
type: "image" | "text"
value: string
}

then replace if(IsImage(chat.avatar)) with if(chat.avatar.type == "image")